This invention relates generally to fastening devices and more particularly to a device having a clip for attachment to a panel and a nut for receiving a threaded bolt.
There are many instances, especially in blind locations, where a nut is desired, but where the operator either cannot hold the nut in place while the bolt is being inserted, or cannot thereafter hold the nut against rotation during the final tightening operation. At the present time, nut clips are widely used in the automotive industry for fastening sheet metal panels. Typically, a U-shaped sheet metal clip is provided, with one leg of the clip formed by extrusion to provide a nut which is subsequently tapped or roll-formed to provide internal threads. The problem with these nut clips is that the threads are often of poor quality and not well formed, as a result of which the bolt is prone to cross-threading and stripping. Poor quality threads are due in part to the hardness of the metal of which the sheet metal clip is formed and also to the thinness of the clip metal. The process of extruding the nut further thins the metal. Also the thin high carbon steel does not draw well so that there is a relatively large radius where the nut joins the clip. As a result, the threads in the radiused portion of the nut are even less well formed.
To avoid the foregoing difficulties, a separate cold-headed nut is sometimes attached to a conventional U-shaped clip, but this is an expensive expedient which has to be ruled out for many applications.
In accordance with the present invention, a nut/clip assembly is provided in which the clip is much like the clips of prior nut/clip assemblies, but the nut portion is made of a different and thicker material than the spring clip portion, giving the nut portion a greater wall thickness. The nut is formed preferably by extruding or drawing a nut blank. The nut is internally threaded, and because the nut is of sufficient wall thickness, the threads are fully formed and of good quality. The nut is secured to one of the legs of the clip preferably by welding. The other leg of the clip extends across the nut and has a bolt-receiving hole aligned with the nut threads.
Preferably, the clip is made of a carbon steel alloy and the nut is made of a carbon steel alloy of lesser carbon content than the clip. In a preferred embodiment, the clip is made of a relatively hard 1045 carbon steel and the nut is made of a softer 1010 carbon steel. The clip is sufficiently resilient to grip a panel. The softer metal of the nut contributes to the formation of high quality threads. Also, the softer nut metal draws well and the radius where the nut joins the clip is quite small so that even the nut threads in this radiused portion are of good quality.
One object of this invention is to provide a nut/clip assembly having the foregoing features and capabilities.
Another object is provide a nut/clip assembly which is strong and durable in use, which has high quality fully formed threads, and which can be easily and inexpensively manufactured.
These and other objects, features and advantages of the invention will become more apparent as the following description proceeds, especially when considered with the accompanying claims and drawings.